The present application relates to a three-dimensional image display apparatus capable of displaying a three-dimensional image.
A two-eye three-dimensional image technology for obtaining a three-dimensional image while both eyes of an observer respectively observe different images called parallax images and a multiple-eye three-dimensional image technology for obtaining a plurality of three-dimensional images from different points of view by preparing a plurality of sets of parallax images are proposed, and a large number of technologies related to the above-mentioned technologies are developed. However, according to the two-eye three-dimensional image technology or the multiple-eye three-dimensional image technology, a three-dimensional image is not located at an intended space as a three-dimensional image, but the three-dimensional image exists on a two-dimensional display surface, for example, and is regularly located at a fixed position. Therefore, convergence and accommodation, in particular, which are ocular system physiological responses do not operate simultaneously, and eye fatigue accompanied by the phenomenon causes a problem.
On the other hand, in the real world, information on an object surface propagates to eye balls of the observer with a medium of light rays. Then, as a technology for artificially reconstructing the light rays from the object surface physically existing in the real world, a holography technology is proposed. A three-dimensional image utilizing the holography technology uses an interference fringe generated on the basis of an interference of light and uses a diffraction wave surface itself which is generated when the interference fringe is irradiated as image information medium. Therefore, the ocular system physiological responses such as the convergence and the accommodation similar to those generated when the observer observes the object in the real world are generated, and it is possible to obtain an image with little eye fatigue. Furthermore, the reconstruction of the light ray surface from the object means that continuity is secured with respect to a direction in which the image information is transmitted. Therefore, even when the point of view of the observer is moved, an appropriate image from a different angle in accordance with the movement can be continuously presented, and kinematic parallax is continuously presented.
However, according to the holography technology, the three-dimensional spatial information of the object is recorded as the interference fringe in the two-dimensional space, and the information amount is extremely large as compared with the information amount on the two-dimensional space such as a photograph capturing the same object. This is because it can be considered that the information is converted into the density on the two-dimensional space when the three-dimensional spatial information is converted into the two-dimensional spatial information. For that reason, the spatial resolution used by a display apparatus which displays the interference fringe based on CGH (Computer Generated Hologram) is extremely high, and also the enormous information amount is demanded. Thus, it is technically difficult to realize the three-dimensional image on the basis of a real time hologram.
According to the holography technology, the light rays which can be regarded as the continuous information is used as the information medium, and the information from the object is transmitted. On the other hand, as a technology for generating a three-dimensional image by reproducing with discrete light rays a situation theoretically substantially equivalent to a location composed of light rays in the real world, a light ray reconstruction method (which is also called integral photography method) is proposed. According to the light ray reconstruction method, a light ray group composed of a large number of light rays propagating in many directions are scattered in advance in a space by way of optical means. Next, the light ray propagating from the surface of the virtual object located at an arbitrary position is selected from the light ray group. By modifying the intensity and phase of the selected light ray, an image composed of the light ray is generated in the space. The observer thus can observe this image as a three-dimensional image. The three-dimensional image based on the light ray reconstruction method is obtained through multiple imaging of images from a plurality of directions at an arbitrary point. Similarly to the case of observing the three-dimensional image in the real world, at an arbitrary point, the appearance varies depending on observation positions.
As an apparatus for realizing the light ray reconstruction method described above, an apparatus prepared by combining a flat display apparatus such as a liquid crystal display apparatus or a plasma display apparatus with a micro lens array or a pin hole array is proposed (for example, see Japanese Unexamined Patent Application Publication No. 2003-173128, Japanese Unexamined Patent Application Publication No. 2003-161912, Japanese Unexamined Patent Application Publication No. 2003-295114, Japanese Unexamined Patent Application Publication No. 2003-75771, Japanese Unexamined Patent Application Publication No. 2002-72135, Japanese Unexamined Patent Application Publication No. 2001-56450, and Japanese Patent No. 3523605). In addition, an apparatus in which a large number of projector units are disposed. FIG. 52 shows a configuration example of a three-dimensional image display apparatus using the projector units to realize the light ray reconstruction method. In this apparatus, a large number of projector units 301 are arranged in parallel in a horizontal direction and a vertical direction, light rays different in angles are emitted from the respective projector units 301. With this configuration, through multiple reproduction of a multi view angle image at an arbitrary point in a certain cross section 302, the three-dimensional image is realized.
In addition, Japanese Unexamined Patent Application Publication No. 2007-041504 discloses a three-dimensional image display apparatus including:
(A) light modulation means provided with a plurality of pixels and configured to generate a two-dimensional image by modulating light from a light source by the respective pixels and to emit a spatial frequency in the generated two-dimensional image along diffraction angles corresponding to a plurality of diffraction orders generated from the respective pixels,
(B) Fourier transform image formation means configured to perform Fourier transform on the spatial frequency in the two-dimensional image emitted from the light modulation means to generate a number of a Fourier transform images corresponding to the plurality of diffraction orders,
(C) Fourier transform image selection means configured to select a Fourier transform image corresponding to a desired diffraction order among the number of Fourier transform images as generated corresponding to the plurality of diffraction orders, and
(D) conjugate image formation means configured to form a conjugate image of the Fourier transform image selected by the Fourier transform image selection means.